Download Troubleshooting

Unit 5 Troubleshooting
Unit Objectives
Given a realistic scenario depicting one of several possible machine malfunctions, the learner will be able to effectively
troubleshoot, diagnose and repair the malfunction before returning the machine to normal operation.
Given a machine displaying an error or warning message, all the necessary tools and safety equipment, the learner
will be able to access the programming and use component test menus as a tool to assist in the diagnosing process.
The learner will be able to navigate to the component testing menus. (Test Augers & LAF Menus L & R Refill Threshold and Test Refill)
The learner will be able to access the “Temp and Torque” screen.
Given a list of error and warning messages, the learner will be able to
give an explanation of the error and warning messages.
Given a realistic scenario when product does not freeze or chill, the learner will be able to diagnose other possibilities
other than a failure in the refrigeration system.
The learner will be able troubleshoot the torque (ice) system.
The learner will be able to use the “Temp and Torque” screen as a troubleshooting tool.
The learner will be able to troubleshoot the chill mode.
Troubleshooting
Test Menus
The ULTRA machine features a few testing menus. Enter programming and navigate to the menus to test the auger
motor in forward and reverse rotation and check the operation of the LAF product level circuit and water valve for
electrical activation.
Test Augers
This function tests the operation of forward and reverse of each auger motor. Left auger appears first. Press the ICE
hidden switch to toggle between OFF, FORWARD and REVERSE. Press GOURMET hidden switch to repeat the
operation for the right auger motor. A one minute time out will return to the Home Screen.
Select NEXT to repeat process for Right Auger Test.
Note: ULTRA-1 models will only have one test screen.
Refill Threshold (Ultra with LAF Kit Installed)
This function allows the operator to adjust the Refill Threshold depending on the type of product being dispensed.
Test Refill: Test menu by turning on the output to the corresponding water valve.
The water threshold is factory set at 155, a common threshold used throughout the Bunn beverage equipment. The
number on the left can be used as a tool to see the operation of the refill circuit and can be adjusted accordingly to
the conductivity (TDS) of the product or water. The threshold 155 normally will not need to be adjusted on the Ultra
machine but is mainly for geographical areas where naturally soft water is present or customers using water purification systems (reverse osmosis) on coffee equipment.
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Example: Product reads “8 on L REFILL 155” menu when product is touching level probe. Product leaves level
probe and the 8 starts increasing in value, the number will go higher than the threshold of 155, the CBA will activate
the refill circuit to turn on and fill the hopper. Once product touches the level probe, the product number reading on
the left will come down below the threshold setting number 155 and indicate to the CBA that the level probe is satisfied (number < 155) with product. The refill circuit is satisfied and will turn off.
Number range 0 – 255
Threshold 155 – adjustable for natural soft water condition or use of water filter purification.
Reading < than 155 means satisfied or shorted circuit
Reading > than 155 means call for refill or open circuit
Temp and Torque Screen
Press and hold for five seconds the ULTRA and ICE hidden switches to display the TEMP & TORQUE. The temperature of each cooling drum and the hot gas temperature will toggle back and forth. The auger torque is displayed
continuously during machine operation. Press and release the ULTRA and ICE hidden switches to return to HOME
SCREEN. The TEMP & TORQUE mode is typically used for service.
Notice: While in the TEMP & TORQUE screen, the UPPER/lower case will be replaced by symbols. The symbol is
used for reference, illustrating when the solenoid is on or off. The screen can be used to see the possibility of a dirty
filter or the condition of the auger shaft torsion springs by the thickness setting multiplied by three during machine
operation. No load on the auger shaft torsion spring during rotation will start from thickness setting multiplied by three
and countdown to zero. If zero is not achieved and a number is represented, this is an indication of a worn torsion
spring in the auger shaft.
Warning Messages
Clean Filter Message
A monthly counter will automatically show the warning message to clean the condenser filter. If the filter is not
cleaned and the machine detects a rise in temperature, the message will escalate to the next level of cleaning the
filter and eventually will disable the machine from freezing (ice).
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The machine will also display the number of day’s pass due on the display.
3SECSTOCLEAR
Clean Due Today Message
The messages come from the activation of the “Days To Clean” menu. It can be set up as a clean message only or
set as a clean lockout. To reset the Clean Due Today message or lockout, two functions must be performed. Either
power off the dispenser using the I/O (ON/OFF) switch and allow the barrels or cooling drums to warm over 50°F.
Scroll to the Cleaning Guide and perform the cleaning service. The barrels will warm to over 50°F when cleaned with
warm water and the message will disappear.
CleanDueToday
CLEANDueNow
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Error Messages
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Product Does Not Freeze or Form Ice Crystals
When the product does not freeze, there are several possibilities other than a failure in the refrigeration system.
1. Product is very high in brix (sugar) or alcohol.
2. The torque between the auger motor and the frozen product is controlled by the torque sensor board measuring
the distance between the pins on the coupler and shaft. When the distance between the pins reaches the maximum
allowable distance, the compressor shuts off. The machine thinks the product thickness has reach the maximum and
shuts off the compressor. The illustration below shows some of the other possible causes for a false reading from the
torque sensor board.
Normal Operation
Possible Causes for False Readings
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Torque Sensor Board
The motor pin and auger shaft pin rotate between the LED (red) and photo transistor on the board, interrupting the
infra red beam. The microprocessor calculates the distance between the pins and determines the refrigerant solenoid
shut off point based on the programmable “thickness” setting per side.
Troubleshoot the torque board by blocking
and unblocking the infra red with an object
while monitoring with a voltmeter. If the meter
displays 5vdc when blocked and 0vdc when
unblocked, then the Torque Sensor is good. If
there is no 5vdc reading, verify that both red
and white sensors are clean.
Blocked – 5 vdc
Unblocked – 0 vdc
Thermistor
The thermistor or temperature sensors are
located inside the top rear of the cooling drum.
The resistance value changes according to
barrel temperature which correlates a change
in voltage. The “Temp and Torque” screen can
be used to see barrel temperature. The thermistor can be checked by resistance or voltage. Connect a voltmeter,
across the two leads of the temperature sensor (leave plug connected);
The indication must be:
a) Approx. 1.4 vdc @ 71° F
b) Approx. 2.6 vdc @ 32° F
If voltage reading is 0v, the Control Board is not supplying the necessary 5v and should be replaced. If the reading
stays at 5vdc, replace thermistor.
Resistance Check
Disconnect the plug on thermistor leads and check resistance as indicated below.
The indication must be:
a) 5650 ohms @ 32° F ± 10%
b) 2000 ohms @ 77° F ± 10%
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Ultra PAF Error Messages
Door Lamp
Fault
On
Normal operation the Powder Autofill is ready to
dispense.
Flashes On/Off at 50% duty cycle
Low product level in Powder Autofill hopper.
Two flashes about every 2 seconds
Ultra/Powder Autofill probe circuit open.
Three flashes about every 2 seconds
Powder Autofill hopper not in place.
Four flashes about every 2 seconds
Ultra refill exceeded 5 minutes.
Off
Door not closed.
Ultra 1 Triac Map
5
1
2
3
4
1. TH1 = Auger
2. TH2 = Compressor Relay
3. TH3 = Refrigeration
4. TH4 = Refill Valve (not currently offered)
5. Q4 = Fan
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Ultra 2 Triac Map (Bunn P/N 38710.xxxx)
1
2
3
4
5
6
1. TH6 = Right Auger
2. TH5 = Left Auger
3. TH4 = Right Refrigerant Valve
4. TH3 = Fan
5. TH2 = Compressor Relay
6. TH1 = Left Refrigerant Valve
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Ultra LAF Triac Map (Bunn P/N 38983-0000)
1
2
1. Right Fill Valve (TH1)
2. Left Fill Valve (TH2)
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